THERMAL-STABILITY AND MICROMAGNETIC PROPERTIES OF HIGH-DENSITY COCRPTTA LONGITUDINAL MEDIA

Micromagnetic and magnetic force microscopy (MFM) studies of high-dens ity longitudinal media are carried out in relation to recording perfor mance and thermal stability. The MFM technique is demonstrated to prov ide information on not only micromagnetics but also on recording param eters such as signal and signal-to-noise ratio comparable to those obt ained using a read head. Annealing experiments are performed on wide ( 3.5 mu m) and narrow (0.8 mu m) track bits written onto CoCrPtTa to ac celerate the thermal reversal process. The written marks are predicted to be unstable for the measured medium magnetic anisotropy energy. Ho wever, comparison of the MFM images of the same patterns before and af ter the anneal reveals no significant degradation with annealing up to 490 K for 12 h. For more extreme annealing conditions, degradation is shown to start not only at the track edges but also between the bits.